demo13

#!/bin/bash
# escaped.sh: 转义字符

echo; echo

echo "\v\v\v\v"      # 打印出 \v\v\v\v literally.
# 用带着选项-e的'echo'会打印出转义字符串.
echo "============="
echo "VERTICAL TABS"
echo -e "\v\v\v\v"   # 打印四个垂直的制表符.
echo "=============="

echo "QUOTATION MARK"
echo -e "\042"       # 打印出字符" (引号, 它的八进制ASCII码为42).
echo "=============="

# 当使用像$'\X'的结构时，-e选项是多余的.
echo; echo "NEWLINE AND BEEP"
echo $'\n'           # 新行.
echo $'\a'           # 警告 (蜂鸣).

echo "==============="
echo "QUOTATION MARKS"
# 版本2开始Bash已经允许使用$'\nnn'结构了.
# 注意在这里,'\nnn'表示一个八进制的值.
echo $'\t \042 \t'   # Quote (") framed by tabs.

# 使用$'\xhhh'结构也可以使用十六进制数来转义.
echo $'\t \x22 \t'  # Quote (") framed by tabs.
# 多谢Greg Keraunen指出这个..
# 早期的Bash版本允许用'\x022'.（译者注，现在不行了）
echo "==============="
echo


# 用ASCII码值把字符赋给变量.
# ----------------------------------------
quote=$'\042'        # 引号"被赋给变量quote了.
echo "$quote This is a quoted string, $quote and this lies outside the quotes."

echo

# 用连串的ASCII码把一串字符赋给变量..
triple_underline=$'\137\137\137'  # 137是字符'_'的ASCII码.
echo "$triple_underline UNDERLINE $triple_underline"

echo

ABC=$'\101\102\103\010'           # 101, 102, 103分别是A, B, C字符的八进制ASCII码.
echo $ABC

echo; echo

escape=$'\033'                    # 033是ESC的ASCII码的八进制值
echo "\"escape\" echoes as $escape"
#                                   不可见的输出.

echo; echo

exit 0